Update instructions - final

tests/test_config_isolation.py

@@ -0,0 +1,39 @@
+"""Suite-wide isolation of `Settings` from developer environment files.
+
+`Settings.model_config` declares `env_file=".env.production"`, resolved relative to the
+current working directory. Running pytest from the repository root therefore loads a real
+developer env file into tests that construct `Settings(...)` directly, and the declared
+field defaults stop being what the suite actually exercises.
+
+That breaks verification in both directions: tests asserting default behavior fail locally
+for environmental reasons, and tests asserting configured behavior can pass locally against
+values that do not exist in CI. The autouse fixture in `conftest.py` neutralizes the class
+level `env_file` so defaults are authoritative; tests that need file loading still pass
+`_env_file=` explicitly, which takes precedence over the class config.
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from transcription.config import Settings
+
+
+def test_settings_defaults_are_not_overridden_by_a_local_env_file():
+    """A bare `Settings(...)` must observe declared defaults, not developer machine state."""
+    settings = Settings(openrouter_api_key="test-key")
+
+    assert settings.environment == "development"
+    assert settings.log_dir == Path("./data/logs")
+    assert settings.host == "0.0.0.0"
+    assert settings.port == 8000
+
+
+def test_explicit_env_file_still_loads(tmp_path):
+    """Isolation must not disable env-file loading for tests that opt into it."""
+    env_path = tmp_path / ".env"
+    env_path.write_text("PORT=9123\n", encoding="utf-8")
+
+    settings = Settings(openrouter_api_key="test-key", _env_file=env_path, _cli_parse_args=False)
+
+    assert settings.port == 9123